The year is 1955, and a great flood is coming to Northfork, Montana. A new hydroelectric dam is about to be installed in the mountains above the town, ready to submerge the valley in the name of progress. It is the charge of a six-man Evacuation Committee to relocate the townsfolk to higher ground. Most have duly departed, but a few stubborn stragglers remain – among them a priest caring for a sickly orphan, a boy whose fevered visions are leading him to believe he is a member of a roaming band of lost angels desperately searching for a way home.